I don't believe the US would use a nuke first for any reason today. I do believe the US has built and is refining conventional high explosive, hardened bunker buster bombs and the way they would be used to dig out a deep bunker would be the use of multiple high precision bombs one after the other to really get down deep. At least that's what I would do.
I do not agree with this statement. Sure, some would but I do believe the majority of the population would like nothing better than to see the current regime fall in tehron. I met some Iranians recently when I was in Australia who were very nice people and were sad about the way things were in their home country. It is very sad that people that just want to live their lives in peace have to flee their country because of their repressive governments.